Wide open @F4.5 the Sigma 12-24mm isn't the sharpest lens and it has some focusing problems but I usually use it manually focused to infinity and at F8 in order to get the best results possible out of the lens. Contrast and colors are quite nice and it doesn't need too much work processing the RAW files. I'm really happy with that lens.

It was quite cold and cloudy that night but at night clouds aren't as bad as at day where shots tend to look too grey.